The present disclosure relates to a developing device used in an image forming apparatus such as a copier, printer, facsimile machine, or the like. More particularly, the present disclosure relates to a method for suppressing clogging of a gap between a developing roller and a regulating blade with developer.
A conventionally common developing system adopted in image forming apparatuses using an electrophotographic process typically uses powdery developer and involves a process of visualizing an electrostatic latent image formed on an image carrier such as a photosensitive drum with the developer, then transferring the visualized image (toner image) to a recording medium, and then fixing the image.
Developer is broadly classified into two-component developer comprising toner and magnetic carrier and one-component developer comprising non-magnetic or magnetic toner alone. As a development system using magnetic one-component developer, what is called a jumping one-component development system is known in which a fixed magnet with a plurality of magnetic poles is arranged inside the developing roller to carry toner in a developer container onto the developing roller using a magnetic carrying force and then thin toner layer is formed by regulating the layer thickness using the regulating blade to let toner fly to a photosensitive drum at a developing position.
In the magnetic one-component development system, the sufficient magnetic force is required at the tip end of the regulating blade for ensuring stability of the toner layer on the developing roller and for improving performance of electrostatic charging of toner. Thus, there is a known technique in which the magnetic force at the tip end of the regulating blade is enhanced by attaching a blade magnet on the side face of the regulating blade. However, attaching the blade magnet makes the toner likely to agglomerate inside the developing device around the blade magnet and at the tip end of the blade. As a result, the toner layer on the developing roller is disturbed and this makes an image failure such as white streaks likely to occur.
To avoid this, there is a known method for suppressing toner agglomeration in which a developer carrier is rotated reversely within a predetermined range when a temperature sensing member for sensing the temperature of the regulating member senses a temperature higher than a predetermined value. There is also a known method for improving the degradation of image quality due to a decline in image density and fogging with a white portion by, according to the environment and status of use of the image forming apparatus, changing the arrangement angle of a magnetic field generation means with a plurality of magnetic poles arranged inside the developer carrier.